Non-heme-metal-containing oxygenases have been shown to be involved in a large number of metabolic processes in both mammalian and bacterial systems. The broad objective of our program is to continue our analysis of the involvement of non-heme iron in the catalytic pathway of the bacterial dioxygenases, protocatechuate-3,4-dioxygenase (PCD), and catechol dioxygenase (CTD), and to carry out comparative studies with the mammalian non-heme iron monooxygenase, liver phenylalanine hydroxylase (PAH), the mammalian copper monooxygenase, dopamine-Beta-hydroxylase (DBH), and the bacterial non-heme iron monooxygenase, P. olevorans epoxidase/hydroylase (POEH). The major spectroscopic technique to be used in these studies is extended X-ray absorption fine structure (EXAFS) spectroscopy. Among the specific aims are (1) to use EXAFS to identify the nature, number, and distances of iron and copper-binding ligands; (2) to examine the interaction of active site metals with substrates, inhibitors, cofactors, and transition state analogs; (3) to draw on our experience in designing transition state analogs by examining new classes of compounds designed to mimic catalytic intermediates, and also to trap functionalities which participate in catalysis and/or are freed due to ligation alterations during the catalytic cycle. Information of the type we propose to obtain is essential to an understanding of molecular basis of non-heme metallo oxygenase catalysis and the design of specific effectors for these important enzymes.